<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .body,
    ul {
      margin: 0;
      padding: 0;
    }
    ul {
      list-style-type: none;
    }
    ul li {
      width: 100px;
      height: 100px;
      border: 2px solid red;
      margin: 20px;
      float: left;
    }
    .item {
      height: 100%;
      background-color: khaki;
    }
    .item1 {
      /* 顺时针旋转到30deg */
      transform: rotate(30deg);
    }
    .item2 {
      /* 逆时针旋转到30deg */
      transform: rotate(-30deg);
    }
    .item3 {
      /* 顺时针旋转到180deg */
      transform: rotate(180deg);
    }
    .item4 {
      /* 顺时针旋转30deg */
      transform: rotate(450deg);
    }
  </style>
  <body>
    <ul>
      <li>
        <div class="item item1">30deg</div>
      </li>
      <li>
        <div class="item item2">-30deg</div>
      </li>
      <li>
        <div class="item item3">180deg</div>
      </li>
      <li>
        <div class="item item4">450deg</div>
      </li>
    </ul>
  </body>
</html>